In the art of machine knitting, it is common practice to employ many thousands of like elements in one given machine such as needle bed slots, jacks, needles and the like. A defect or abnormality in any of these elements can result in damage to the fabric being produced or have an adverse effect on the productivity of the machine. Heretofore, detection devices have been employed for specific abnormalities such as broken needle latch detectors or the like, and devices were known for detecting yarn or fabric discontinuity. Aside from being limited as to the specific defects to which they could respond, the prior art detection devices in many cases responded only after a defect had arisen in the fabric.